In the past helicopters built by Kaman Aerospace Corporation have used what is called a servo tab to help control the collective and cyclic pitch of main rotor blades. These servo tabs are essentially aerodynamic control surfaces mounted to the back of the rotor blades at about 70% rotor diameter that provide rotor blade pitch up and pitch down moments to control the blade pitch. The position of the servo tabs is driven by control rods or cables from a swash plate similar to other conventional helicopters.
Also in the past, electronic “swash plates” have been used to provide electrical control and power to achieve collective and cyclic main rotor blade control but generally only on very small rotors because of the power requirements. Perhaps the closest two disclosures to the current invention as it relates to helicopter rotors was disclosed in U.S. Pat. No. 5,409,183, incorporated herein by reference, and in a Friedrich K. Straub paper.
Also in the past, trim tabs have been used to reduce trim loads on aircraft control surfaces.